THESIS

S. nigrum has hexaploid expected genome size, the histrogram of accession
TS02930 of S. nigrum showed the hexaploid (Figure 15). This result confirms that S.
nigrum is hexaploid species and has more nuclear DNA than tetraploid (S. villosum)
and diploid (S. melongena, S. torvum and S. americanum) species.
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The interspecific hybrids among leafy Solanum species are shown in Figure 15
to 18. As expected genome size of interspecific hybrid S. americanum (2n) and S.
nigrum (6n) should be tetraploid (4n). The histrogram of S00269 x TS02930 is near to
diploid, this indicates that the hybrids are not true hybrids. In contrast the hybrid of
TS02930 x S00861 is shown as tetraploid genome size. This indicates that this hybrid
is true hybrid.
The genome size of interspecific hybrid S. villosum (4n) and S. americanum
(2n) should be triploid (3n). The histrogram of S00854 x S00269 is near to diploid,
this indicates that this hybrid is not true hybrid. In contrast the hybrids of S00854 x
S00861 and S00854 x S00865 showed triploid genome size. This indicates that this
hybrid is true hybrid (Figure 16). Likewise the interspecific hybrid of S. villosum and
S. americanum are shown in Figure 17. The hybrids of TS02600 x S00861 and
TS02600 x S00865 showed the triploid genome size. This indicates that this hybrid is
true hybrid. No significant differences are found among accessions of female parent
that belonging to S. villosum.
The interspecific hybrid between S. villosum and S. americanum when used S.
villosum as male and female parent (S00860 x S00859 and S00861 x S00860),
showed the same histrogram of intermediate of hybrids even in reciprocal crosses.
However, as expected genome size of the interspecific hybrids between S. villosum
and S. nigrum should be pentaploid but the hybrid of S00860 x TS02930 could not
confirm (Figure 18). It might be the leaf sample was too old and contaminated with
some heavily loaded, which decrease the purity of intact nuclei and could not showed
the DNA content of hybrid (Lee and Lin, 2005).